Preheating system for internalcombustion engines



Aug. l, 1950 w. B. coRcoRAN 2,517,464

PRmaEATING SYSTEM Foa mmzNAL-corusmon ENGINES Filed may 24, 1949 /IIIIIIII/,l//IIIIJ I/lII/,I/IIIIII Patented ug.. l, 1950 STATES PATENT OFFICE PBEHEATING SYSTEM FOB INTERNAL- COMBUSTION ENGINES Application May 24, 1949, Serial No. 95,092

(Cl. 12S-142.5)

'i Claims.

The present invention relates to a system for preheating the liquid coolant and the lubricating system of a liquid cooled internal combustion engine to enable such an engine to be started in. cold climates where temperatures may drop to as low as minus 65 Fahrenheit.

Preheating systems long known in the prior art have generally employed a thermo-syphon circulating device in the form of an externally ilred heater having an inlet and outlet connected by piping to the water jacket of the engine and may include a radiator positioned in the engine oil sump in contact with the lubricating oil. The

` radiator serving as a lubricating oil heater has been placed either in series or parallel with the ilow to and from the engine cooling system. The main disadvantage of the prior proposals is the fact that the large body of cold liquid shunted across the heater impedes circulation through the heater resulting in boiling in the heater. Further since the heated liquid tends to rise it is difficult to force liquid down through the oil heating radiator prior to its delivery to the engine water jacket.

In accordance with the present invention a conventional oil fired heater is employed to which a substantially closed circulating conduit is connected and having an oil heating radiator connected in series therein. Since only a small quantity of liquid is in the circulating loop at any one time rapid thermo-syphon circulation is s et up therein by the heater. The closed loop is connected to the engine cooling system by a single lateral conduit positioned at the point of highest elevation in the circulating loop and adjacent the delivery side of the heater. The single lateral conduit is positioned in its connection to the engine cooling jacket such that the loop will be filled with cooling liquid by gravity flow and serves simultaneously in delivering heated liquid to the engine cooling jacket and transferring cold liquid from the cooling jacket to the circulating loop.

With the above description of the invention in view other features and objects will become apparent by reference to the detailed description hereinafter given when taken in conjunction with the appended drawings in which:

Fig. 1 is a side elevation view illustrating an engine preheating system in accordance with the invention;

Fig. 2 is a view partly in section illustrating details of a heater regulator employed in the system of Fig. 1.

Referring now to Fig. 1, the reference numeral I generally indicates an internal combustion engine of conventional type having a block 2 and head 3 each provided with interconnected passages adapted to contain a suitable engine coolant to be circulated therethrough and an oil pan l adapted to contain the engine lubricating oil Supply.

A heater assembly generally indicated at 5 is positioned adjacent the engine and includes a casing 6 having air inlet apertures 1 adjacent the bottom thereof and an exhaust stack 1 at its upper end for discharge of products of combustion to the atmosphere. Air passing upwards from the inlet apertures 1 is in part deflected by an annular curved deiiector B downward into the vaporizing bowl 9 of a conventional pot type oil burner the deiiector and bowl of which are supported from the casing Ii by suitable brackets such as indicated by reference characters IU and II, respectively. 'I'he burner pot 9 is provided with a passage I2 near its bottom adapted to be connected to a fuel supply conduit I3. The burner pot 9 has sloping sides such that the surface area of fuel in the burner pot may be considerably varied by changing the level of fuel and thus control the rate of fuel consumption and hence the burner heat output.

After the fuel in the bowl 9 is ignited. by a torch the heat of combustion induces a draft upwards through the heater casing and deilector l diverts suicient air into the burner pot 9 to mix with vaporized fuel to form a combustible mirture which burns within and above the burner D0 9.

In order to regulate the level of fuel in the burner pot 9 the inlet fuel conduit I3 is connected to a fuel regulator generally indicated by the reference character I5 in Fig. 1.

The fuel level regulator I5 as seen in 2 consists of a rectangular casing I6 serving as a reservoir for burner fuel and having the fuel delivery conduit I3 connected thereto by a suitable pipe connection. A pair of vertical rod guides II are positioned in the housing I6 and have a frame I8 slidably mounted thereon, the frame being suitably threaded to receive the threaded portion I9 of a lead screw 20 which extends through the casing I6 and is adapted to be manually rotated by means of a knob 2l. The frame I8 has a cylindrical valve body 22 mounted thereon, the valve body being connected at its lower end to a flexible conduit 23 to provide an inlet for fuel to the valve body. The valve body 22 is also provided with discharge ports 24 and a conventional needle valve 25 which is axially shiftable with respect to the valve body to vary the discharge of liquid through the ports 24. The needle valve 25 is connected by a 4link 26 to one end of a valve actuating rod 21 having a float 28 mounted on its other end. 'Ihe valve actuating rod 21 is pivotally mounted at 23 on a supporting lug 30 forming an integral part of frame I8.

The flexible conduit 23 is connected at its inlet end to a valve block 32 which is provided with a fuel inlet passage 33 connected to a fuel supply conduit which is connected to a fuel tank (not shown). The inlet passage 33 terminates in a port in the bore 35 in the valve block. A conventional spool type piston valve 36 is axially slidable in the bore 35 and in the position shown directs fuel from pasage 33 to a delivery passage 31 communicating with the valve bore 35 and with the flexible conduit 23. When the valve 36 is moved down from the position shown in Fig. 2 the upper valve head cuts oil fuel delivery to passage 31 and a second delivery passage 38 is uncovered by movement of the lower valve head permitting fuel from passage 33 to flow through passage 3 8 to a conduit 40 to a valve body 4I having delivery ports 42 flow through which is controlled by the position of needle valve 43. 'I'he valve 43 is connected by a link 44 to a float rod 45 pivoted at 46 on a bracket 41 formed integrally with the valve body 4I. The float rod 45 has a float 50 secured thereto which is adapted to actuate the needle valve 43 to control the level of fuel in the housing I6 in accordance with a predetermined minimum level determined by the vertical positioning of the float 50.

The valve 36 has a stem 5l directly connected to a metal bellows 52 suitably supported at its upper end so that expansion of the bellows moves the valve stem downward. Downward movement of the bellows 52 is opposed by a control spring 53, the biasing force of which is adjustable by means of an abutment 54 which is adjustable by conventional screw means not shown. The bellows 52 is connected by means of a small bore tube 55 to a thermometer bulb 56 shown in Fig. l inserted in the engine cylinder head so; as to be responsive to coolant temperature.

The heater casing 6 has a shell type boiler 60 positioned above the burner pot 3 and has an outlet conduit GI connected to a pipe 62 which is coupled to a T fitting 63 which has a lateral extension 64 screwed into the engine block and communicating rwith the cooling water space. 'I'he T fitting 33 is further connected in series with a conduit 65 coupled to a finned tube radiator or heat exchanger 66 positioned in lthe oil pan 4 of the engine I. The radiator 65 is further-connected by means of a pipe 51 to the inlet connection of the boiler 53.

. Operation in the burner pot 3. Fuel from the supply tank is then turned on through a suitable valve and flows into the feed line 34, through passages 33 and 31 of valve assembly 32 into the exible conduit 23 and the float actuated valve body 22. Fuel will then flow freely out of the ports 24 in the valve body 22 until the fuel level rises and.

causes float 28 to rise causing the needle valve 25 to move down to control the inlet of fuel to maintain a substantially constant level of fuel in the casing I6 and a corresponding level in the burner pot 9. The knob 2| may thereafter be actuated to raise the burner pot fuel level to increase the burner output to a desired higher output.

The heated air rising in the heater casing I heats the coolant liquid in the boiler 50 and induces a thermo-syphon circulation through from the boilerfoutlet 6I to conduit 52, T fitting 53, conduit 65, radiator 65 and conduit 61 back to the boiler inlet 58, forming with the boiler or heating element a circulating loop.

Heated liquid passing into the T fitting 53 in part passes into the lateral pipe connection 54 and enters the engine block 2 and simultaneously cool liquid from the engine block passes through the same lateral pipe connection into the liquid circulating through the T fitting and moves downstream into conduit 65. The heated liquid passing through the radiator or heat exchanger 65 heats up the engine lubricating oil and returns to the boiler for heating and recirculation. Since the mass of liquid in the circulating loop is small compared to the volume of liquid in theY engine cooling system thermo-syphon circulation through the loop is very rapid and the transfer of hot liquid to and cold liquid from the engine block is directly proportional to the difference in temperature between the hot and cold liquids.

The exact scientific explanation of the reason why hot and cold liquids will simultaneously flow through the single lateral pipe connection 54 between th'e circulating loop and the engine cooling jacket is not known but temperature measurements taken at the top and bottom of the lateral pipe connection indicate that heated liquid flows in through the upper part of the pipe I4 and cool liquid out through the lower part of the pipe which indicates that a secondary thermosyphon action may be taking place in the lateral conduit. By making the T connection 33 of transparent material a violent ebullition 'or slugging action was observed and the phenomena may be caused at least in part by vapor bubbles expanding and suddenly contracting in the lateral pipev and adjacent portions of the engine cooling jacket. The flow at the T fitting was so turbulent that any attempt to check uid currents by introducing coloring matter into the heated liquid just ahead of the T connection would have been useless.

Test work with equipment in accordance with the invention has conclusively proven that the circulation of fluid in the loop as well as the transfer'of liquid to and from the engine cooling system is very rapid when the temperature difference between the boiler outlet and the engine block coolant is high and the circulation becomes self-regulating, decreasing as the temperature di'erence decreases.

Military uses in Arctic climates require that not only the engine be preheated for ease of starting but thatafter being preheated to the necessary temperature the heating system should be capable of automatically providing stand by operation for long periods of time and for such conditions the temperature responsive control means come into action. Once the coolant temperature in the engine block reaches a desired value such as l00 F. rise above ambient temperature the vapor or fluid pressure in the thermometer bulb 56 increases so that bellows 52 expands and develops sufficient force to overcome the biasing force exerted by the control spring 53 and moves the valve. 36 down from the position shown in Fig. 2. The valve 36 then blocks flow of fuel from passage 33 to passage 31 and diverts the flow to passage 38 from whence it flows into valve body 4I. When the fuel level in housing I6 drops to the predetermined low level iloat 50 becomes effective to control the needle Valve 43 to maintain the fuel level in the housing I6Y and corresponding level n the burner pot 9 to supply justsuilicient heat to maintain the coolant temperature at the desired level for long stand by periods and overcome the effects of radiation and l conduction of heat to the ambient atmosphere.

While the drawings illustrate the use of a known pot type of oil burner which is advantageous in that no electrical equipment is neces- 'sary with such a burner, it is to be understood that the same type of thermal responsive control may be applied to other types of burners.

I claim:

1. A heating system for preheating the liquid coolant of an internal combustion engine comprising a heat exchanger having a liquid inlet and a liquid outlet, means for applying heat to said heat exchanger, a conduit connecting the outlet and inlet oi' said heat exchanger and forming with the heat exchanger a closed loop for thermal circulation of fluid therein and a single conduit connecting the cooling system of the engine to said loop and serving as the sole means for the transfer of coolant to and from the engine cooling system to said closed loop.

2. A heating system as claimed in claim 1, in which the single conduit connecting the uid circulating loop to the engine cooling system is connected to the conduit in said loop adjacent the outlet of the heat exchanger and to the cooling system of the engine such that the loop is maintained filled with engine coolant.

3. The structure as claimed in claim 2, in which a second heat exchanger is provided serially connected in said iiuid circulating loop between the connection of said single conduit thereto and the inlet of the first named heat exchanger, the second heat exchanger being adapted to contact the engine lubricating' oil to transfer heat thereto.

4. A system for preheating the coolant liquid in a liquid cooled internal combustion engine comprising a closed loop for thermo-syphon circulation of the cooling liquid, said loop including a heater having a liquid passage therein provided with an inlet and an outlet and a circulating conduit connected to the heater inlet and outlet, and a parallel connection between said closed loop and the cooling system of the engine, said parallel connection being a single lateral conduit connected to said circulating conduit at the point of highest elevation thereof and adjacent the outlet of said heater, the lateral conduit being connected to the engine cooling system ata point such that the circulating loop will be maintained filled with cooling liquid and' serving as the sole means for transfer of heated liquid from the circulating loop to the engine cooling'system and cold liquid from the engine cooling system to the circulating loop.

5. The structure as claimed in claim 4, including a radiator positioned in the lubricating oil reservoir of the engine, said radiator being serially connected in the path of iiow in said circulating loop between the connection of the lateral conduit thereto and the inlet to the heater, said radiator being adapted to transfer heat to the engine lubricating oil.

6. The structure as claimed in claim 5, in which the heater is of the internal combustion type having a liquid fuel burner therein, a source of fuel, a regulator interposed betweenthe source and burner for controlling the rate of fuel supply to the burner to maintain the supply rate substantially at a constant predetermined value and` means responsive to engine coolant temperature for reducing the fuel supply to the burner to a predetermined minimum value when the engine coolant reaches a desired temperature.

7. A system for preheating the liquid coolant and the lubricating oil supply of an internal combustion engine comprising a liquid fuel combustion heater having a uid passage therein with a fluid inlet and an outlet, a radiator positioned in contact with the engine oil supply, conduit means connecting said radiator in series flow relation to said heater inlet and outlet to form a fluidi circulating circuit, means connecting said circuit to the engine cooling system to continually divert a portion of the heated fluid in said circuit to the engine cooling system and supplying coolant from the engine cooling system to the circuit, means for supplying fuel at a substantially constant predetermined rate to said combustion heater and means responsive to the engine coolant temperature for reducing the rate of fuel supply toa predetermined minimum value when the coolant temperature reaches a desired value.

i WILLIAM B. CORCORAN.

REFERENCES CITED The following references are of record in the flle of this patent:

UNITED STATES PATENTS Number Name Date 1,258,068 Wetzler Mar. :5, 1918 1,460,668 Good July 3, 1923 1,608,537 Swanberg Nov. 30, 1926 2,021,569 Paseo Nov. 1.9, 1935 

